Contact Lenses Made With HEMA-Compatible Polysiloxane Macromers

ABSTRACT

Optically clear silicone hydrogel contact lenses are described that comprise a polymeric lens body that is the reaction product of a polymerizable composition comprising at least 25 wt. % of at least one hydroxyalkyl methacrylate; and at least 20 wt. % of at least one HEMA-compatible bifunctional polysiloxane comprising at least 6 siloxane groups and having an HLB value of at least 5 and/or a hydroxyl group content of at least 1 wt. %.

This application claims the benefit under 35 U.S.C. §119(e) of priorU.S. Provisional Patent Application Nos. 61/694,011, filed Aug. 28,2012, and 61/786,761, filed Mar. 15, 2013, which are incorporated intheir entireties by reference herein.

BACKGROUND

The field of the disclosure is contact lenses formed fromcopolymerization of a hydroxyalkyl methacrylate with a HEMA-compatiblebifunctional polysiloxane.

2-hydroxyethyl methacrylate (HEMA) is a biocompatible, polymerizablemonomer that has been used for over the past forty years to make softhydrogel contact lenses. HEMA-based hydrogel contact lenses are muchmore comfortable to wear than their rigid predecessors. However, adrawback of the HEMA-based hydrogel lenses is that they have low oxygenpermeability. It was recognized that materials that provide higheroxygen permeability would be healthier for the cornea. In the late 1990ssilicone hydrogel contact lenses, which have significantly higher oxygenpermeability than HEMA-based hydrogel lenses, were introduced to themarket. However, the siloxane monomers used to make silicone hydrogelsare typically much more expensive than HEMA. In addition, the methodsused to make silicone hydrogel contact lenses are substantially morecomplex and labor-intensive than for HEMA-based hydrogel contact lenses.It would be desirable to combine the benefits of HEMA with the oxygenpermeability attributes of silicone hydrogels, however HEMA is veryhydrophilic and is generally not miscible with silicone monomers.

Background publications include U.S. Pat. No. 8,053,544, U.S. Pat. No.8,129,442, U.S. Pat. No. 4,260,725, U.S. Pat. Publ. No. 2011/0181833,U.S. Pat. Publ. No. 20060063852, and U.S. Pat. Publ. No. 2011/0140292.

SUMMARY

We have discovered HEMA-compatible siloxane monomers that can be used tomanufacture contact lenses that combine the attributes of HEMA-basedcontact lenses with the high oxygen permeability of silicone hydrogellenses.

Disclosed herein are optically clear silicone hydrogel contact lensescomprising a polymeric lens body that is the reaction product of apolymerizable composition comprising at least 25 wt. % of at least onehydroxyalkyl methacrylate and at least 20 wt. % of at least oneHEMA-compatible bifunctional polysiloxane. The polysiloxane isbifunctional in that it comprises either two polymerizable acrylate ormeth(acrylate) groups. The polysiloxane further comprises at least 6siloxane groups and i) has an HLB value of at least 5, or ii) has ahydroxyl group content of at least 1 wt. %, or iii) has both an HLBvalue of at least 5 and a hydroxyl group content of at least 1 wt. %.The contact lenses may have any of the additional feature or anycombination of non mutually-exclusive additional features described asexamples in the following paragraphs.

In one example, the HEMA-compatible bifunctional polysiloxane has amolecular weight of 1K to 20K.

In another example, the HEMA-compatible bifunctional polysiloxane has anelemental silicon content of at least 10 wt. %, optionally combined withthe above-described molecular weight feature.

In a specific example, optionally combined with one or both of the aboveadditional features, the HEMA-compatible bifunctional polysiloxane hasthe structure of Formula 1:

wherein R₁ and R₂ are independently selected from either hydrogen or amethyl group, k is an integer of 0 or 1, m is an integer of at least 6,n is an integer of at least 1, p is an integer of at least 1, and R₁ iseither hydrogen or a methyl group. In a further example, m is an integerof 6 to 100, n is an integer of 1 to 75, and p is an integer of 1 to 40.In yet a further example, m is an integer of 6 to 60, n is an integer of1 to 10, and p is an integer of 10 to 30. And in still a furtherexample, m is an integer of 30 to 60, n is an integer 30 to 60, p is aninteger of 1 to 6, and R₁ is hydrogen.

In one example, the HEMA-compatible bifunctional polysiloxane has an HLBvalue of at least 7. In another example, the HEMA-compatiblebifunctional polysiloxane has an HLB value of less than 5 and a hydroxylgroup content of at least 1 wt. %. In yet another example, theHEMA-compatible bifunctional polysiloxane has an HLB value of 2 to 4 andhydroxyl group content of 4 to 8 wt. %.

The polymerizable composition used to make the contact lenses of any ofthe above-described examples or combination of examples may furthercomprise 1 to 65 wt. % diluent, wherein the diluent comprises water, alow molecular weight polyethylene glycol (PEG), or a combinationthereof. In specific examples, the HEMA-compatible bifunctionalpolysiloxane requires water addition for optical clarity.

In any of the preceding examples or combination of examples, thepolymerizable composition may further comprise 0.1 to 5 wt. %methacrylic acid.

In any of the preceding examples or combination of examples, thepolymerizable composition may comprise at least 35 wt. % of thehydroxyalkyl methacrylate.

In any of the preceding examples or combination of examples, thehydroxyalkyl methacrylate may be 2-hydroxyethyl methacrylate (HEMA).

In any of the preceding examples or combination of examples, the contactlens may have a Dk of at least 35. In a further example, theHEMA-compatible bifunctional polysiloxane provides the contact lens withat least a 50% increase in oxygen permeability.

Also disclosed herein is a method of manufacturing an optically clearcontact lens as set forth in any of the above examples or combination ofexamples. The method comprises polymerizing a polymerizable compositionto form a polymeric lens body and hydrating the polymeric lens body,wherein the polymerizable composition comprises at least 25 wt. % of atleast one hydroxyalkyl methacrylate and at least 20 wt. % of at leastone HEMA-compatible bifunctional polysiloxane, and wherein thepolymerizable composition is either diluent-free or comprises about 1 to65 wt. % of a diluent consisting essentially of water or a low molecularweight PEG, or a combination thereof. In a specific example of themethod, the polymeric lens body does not come in contact with a volatileorganic solvent during the hydrating step. In a further example, thepolymerizing step comprises thermal curing in air.

Also disclosed herein is a composition comprising a polysiloxane ofFormula 3:

wherein R₂ is selected from either hydrogen or a methyl group, m is aninteger of 6 to 50, n is an integer of 1 to 6, and p is an integer of 8to 20, and wherein the composition comprises at least 75% of thepolysiloxane and is miscible in HEMA to at least 20 wt. %. In a specificexample, the composition comprises a polysiloxane of Formula 3 whereinR₂ is a methyl group, m is an integer of 6 to 25, n is an integer of 1to 4, and p is an integer of 12 to 18.

DETAILED DESCRIPTION

As a result of extensive research, we have developed HEMA-compatiblepolysiloxane macromers that can be used to manufacture optically clearsilicone hydrogel contact lenses having a high HEMA content.Accordingly, contact lenses can be manufactured using, the polysiloxanemacromers disclosed herein together with HEMA, or otherhydroxyalkyl(meth)acrylate, thereby combining the benefits of HEMA withthe oxygen permeability attributes of silicone hydrogels. Thepolysiloxane is bifunctional, which, as used herein, means that itcomprises two polymerizable acrylate or meth(acrylate) groups. It alsocomprises at least 6 siloxane (SiO) groups, and has an HLB value of atleast 5 and/or a hydroxyl group content of at least 1 wt. %.

By HEMA-compatible, it is meant that the bifunctional polysiloxane formsan optically clear lens made from the following test formulation andprocedure. The test formulation consists essentially of a mixture of 20parts of the bifunctional polysiloxane, 80 parts HEMA, 0.5 partsethylene glycol dimethacrylate (EGDMA), 0.5 parts of the polymerizationinitiator 2,2′-azobis(2,4-dimethylpentanenitrile) (V52), optionally 0.1to 2 parts methacrylic acid (MA), and optionally 0.1 to 30 parts water,where parts are by weight based on the total weight of the testformulation, which is a polymerizable composition. The test formulationis cured in a polypropylene contact lens mold at 80° C. for one hour.After cure, the mold is opened and the resulting polymeric lens body iseither mechanically removed from the mold (i.e. dry-delensed) or iswet-delensed by immersing the mold in water until the polymeric lensbody hydrates and floats off of the mold. After delensing, the polymericlens body is then placed into fresh room temperature water for 20minutes, then placed in a contact lens blister containing 1.8 mlphosphate buffered saline (PBS), sealed, and sterilized by autoclave. Ifthe resulting lens is optically clear after autoclave, the polysiloxaneis demonstrated to be miscible in HEMA to at least 20 wt. % and is thusconsidered to be HEMA-compatible. A lens is considered optically clearif it exhibits at least 90% light transmittance between 381 nm to 780 nm(measured in accordance with ISO 18369). If a bifunctional polysiloxaneresults in a clear lens using the above method except that theformulation has 30 parts of the polysiloxane and 70 parts HEMA, thepolysiloxane is said to be miscible in HEMA to at least 30 wt. %. Invarious examples, the bifunctional polysiloxanes described herein are atleast 25, 30, 35, 40, 45, or 50 wt. % miscible in HEMA. Throughout thisdisclosure a reference to “examples”, “an example” or “a specificexample” or similar phrase, is intended to introduce a feature orfeatures of the contact lens, HEMA-compatible polysiloxane,polymerizable composition, or method of manufacture (depending oncontext) that can be combined with any combination ofpreviously-described or subsequently-described examples (i.e. features),unless a particular combination of features is mutually exclusive, or ifcontext indicates otherwise.

Some of the HEMA-compatible polysiloxanes described herein are misciblein the above test formulation (i.e. the mixture is clear) withoutaddition of any water, but result in a cloudy lens after curing andhydration. We discovered that by adding water to the polymerizablecomposition, the resulting lens will be optically clear. In suchexamples, the HEMA-compatible polysiloxane is said to require wateraddition for HEMA compatibility, though it will be appreciated thatother diluents besides water may also result in an optically clear lens.Thus, in various examples, the polymerizable composition additionallycomprises from about 1, 5 or 10 wt. % up to about 30, 50, or 65 wt. % ofa diluent, wherein the wt. % of the diluent is based on the total weightof the polymerizable composition. As used herein, the term diluentrefers to a non-polymerizable component of the polymerizable compositionthat is added to compatibilize (i.e. make miscible) the polysiloxanewith the HEMA (or other hydroxyalkyl methacrylate). In some examples,the diluent consists essentially of water, a low molecular weightpolyethylene glycol (PEG), or a combination thereof. As used herein, alow molecular weight PEG has an average molecular weight of less thanabout 1500, and in some examples, has an average molecular weight ofless than about 1200, 1000, or 800. In some examples, theHEMA-compatible polysiloxane may be prepared by a hydrosilyationreaction in which a side chain derived from a low molecular weightreactive PEG, such as hydroxyl polyethylene glycol allyl ether, isattached to a polysiloxane as described in Example 2 below. In suchexamples, the hydrosilyation reaction product may comprise at least 70,75 or 80 wt. % of the HEMA-compatible polysiloxane, with the remainingcomponents being PEG and the reactive PEG (e.g. OH-PEG allyl ether). Insuch examples, the PEG and the OH-PEG allyl ether can be removed fromthe HEMA-compatible polysiloxane by further purification to provide aHEMA-compatible polysiloxane having a purity of at least 85, 90, or 95wt. %. An exemplary purification method is described below and inExample 6. Alternatively, the PEG and reactive PEG can remain tofunction as a low molecular weight PEG diluent in the polymerizablecomposition. Thus, the term “low molecular weight PEG diluent”encompasses reactive PEGs (e.g. OH-PEG allyl ether) having an averagemolecular weight of ≦1500 that are used in preparing the polysiloxane.In specific examples, the diluent is substantially free ofnon-polymerizable polysiloxane-containing components, such aspolysiloxane surfactants, silicone oils, or other diluents known for usein silicone hydrogel contact lens formulations. An advantage of thewater and low molecular weight PEG diluents described herein is that thecontact lens can be made without the use of volatile solvents.

The hydrophilicity of a silicone macromer is represented by itshydrophilic-lipophilic balance (HLB) value, which is calculated astwenty times the molecular weight of the hydrophilic portion of thepolysiloxane divided by the total molecular weight of the polysiloxane.For example, a HEMA-compatible polysiloxane may have the structure shownin Formula 1, where R₁ is hydrogen. In such examples, the polyethyleneoxide (PEO; —CH₂CH₂O—) groups and the terminal hydroxyl (—OH) groupsmake up the hydrophilic portion of the polysiloxane. An example of onesuch polysiloxane is described in Example 2 below, designated H10P16,and is represented by Formula 1 below wherein k is 0, m is 19.7, n is2.5, p is 16, R₁ is hydrogen, and R₂ is a methyl group.

Thus, based on these values, the HLB value for H10P16 is calculated tobe about 10.9. In the case of polydisperse molecules, such as thepolysiloxanes described herein, the term “molecular weight” refers tothe absolute number average molecular weight (in units of Daltons) ofthe monomer as determined by ¹H NMR end-group analysis (NMR). Similarly,the values of m, n, and p values are average values as determined byNMR. Thus, in various examples, the HLB value of the polysiloxane is atleast 6, 7, or 8, and up to about 10, 11, or 12. It will be appreciatedthat the polysiloxane may comprise hydrophilic groups instead of, or inaddition to, the PEO and/or hydroxyl groups that contribute to the HLBvalue. Examples of such additional groups include urethane groups, amidegroups, and diol groups.

Throughout this disclosure, when a series of lower limit ranges and aseries of upper limit ranges are provided, all combinations of theprovided ranges are contemplated as if each combination werespecifically listed. For example, in the listing of HLB values above,all 9 possible HLB ranges are contemplated (i.e. 6-10, 6-11 . . . 8-11,and 8-12). Also, throughout this disclosure, when a series of values ispresented with a qualifier preceding the first value, the qualifier isintended to implicitly precede each value in the series unless contextdictates otherwise. For example, for the above HLB values, it isintended that the qualifier “at least” implicitly precedes both 7 and 8,and the qualifier “to about” implicitly precedes both 11 and 12.

While the HEMA-compatibility of a polysiloxane is determined using atest formulation in the manner described above, the polymerizablecompositions used to make the contact lenses described herein maycomprise monomers in addition to hydroxyalkyl methacrylate provided thatthe composition comprises at least 25 wt. % of at least one hydroxyalkylmethacrylate, and at least 20 wt. % of at least one HEMA-compatiblebifunctional polysiloxane comprising at least 6 siloxane groups andhaving an HLB value of at least 5 and/or comprising a hydroxyl groupcontent of at least 1 wt. %. As used herein, a wt. % of a monomer (i.e.the hydroxyalkyl methacrylate, the HEMA-compatible polysiloxane, and anyother polymerizable component of the polymerizable composition) is basedon the total weight of polymerizable monomers in the composition, i.e.excluding diluents and any other non-polymerizable component.

The hydroxyalkyl methacrylate may be any lower hydroxyalkyl methacrylatesuitable for use in contact lenses. In specific examples, thehydroxyalkyl methacrylate is selected from HEMA, 2-hydroxybutylmethacrylate (HOB), 2-hydroxypropyl methacrylate (HOP), and combinationsthereof. For example, in the case of a composition that comprises 10 wt.% HOB and 15 wt. % HOP, the composition is said to comprise 25 wt. % ofat least one hydroxyalkyl methacrylate. In other words, the compositionmay comprise a combination of hydroxyalkyl methacrylates provided thattheir combined total is at least 25 wt. %. Similarly, the compositionmay comprise a combination of two or more HEMA-compatible, bifunctionalpolysiloxanes having an HLB value of at least 5 and/or comprising ahydroxyl group content of at least 1 wt. %, provided that their combinedtotal in the composition is at least 20 wt. %. Thus, reference to “a”,“an” or “the” monomer of a particular type (e.g. “the HEMA-compatiblepolysiloxane” or “a hydroxyalkyl methacrylate”) is meant to encompass“one or more” of said type of monomer unless context dictates otherwise.In various examples, the polymerizable composition comprises at least30, 35 or 40 wt. % of the hydroxyalkyl methacrylate and at least 25, 30,or 35 wt. % of the HEMA-compatible polysiloxane. Other monomers may beincluded in the polymerizable composition in addition to thehydroxyalkyl methacrylate and the HEMA-compatible polysiloxane.Exemplary additional monomers include N-vinyl-N-methyl acetamide (VMA),N-vinyl pyrrolidone (NVP), 1,4-butanediol vinyl ether (BVE), ethyleneglycol vinyl ether (EGVE), diethylene glycol vinyl ether (DEGVE),N,N-dimethylacrylamide (DMA), methyl methacrylate (MMA), ethoxyethylmethacrylamide (EOEMA), ethylene glycol methyl ether methacrylate(EGMA), isobornyl methacrylate (IBM), glycerol methacrylate (GMA),methacrylic acid (MA), acrylic acid (AA) or any combination of two ormore of the foregoing additional monomers. In a specific example, thepolymerizable composition comprises from about 0.1, 0.5, 1 wt. % up toabout 2, 3, or 5 wt. % MA or AA.

A polymerizable siloxane that is not necessarily HEMA-compatible, asdefined above, may also be included in the polymerizable composition upto an amount in which the additional polymerizable siloxane remainsmiscible such that the resulting lens is optically clear. Examples ofadditional polymerizable siloxanes include3-[tris(trimethylsiloxy)silyl]propyl methacrylate (“TRIS”),3-methacryloxy-2-hydroxypropyloxy)propylbis(trimethylsiloxy)methylsilane(“SiGMA”), methyldi(trimethylsiloxy)sylylpropylglycerolethylmethacrylate (“SiGEMA”), and monomethacryloxypropyl functionalpolydimethylsiloxanes such as MCR-M07 and MCS-M11, all available fromGelest (Morrisville, Pa., USA). Other polymerizable siloxanes are knownin the field (see e.g. U.S. Pat. No. 7,572,841, U.S. Pat. No. 5,998,498,U.S. Pat. No. 5,965,631, U.S. Pat. Pub. No. 2006/0063852, U.S. Pub. No.2007/0296914, U.S. Publ. No. 2009/0299022, U.S. Pat. No. 6,310,169, andU.S. Pat. No. 6,867,245, each incorporated herein by reference).

Although the HEMA-compatible siloxane is bifunctional, and thusfunctions in the polymerizable composition as a cross-linker, anadditional cross-linker may be included in the polymerizable compositionto achieve a hydrogel having the physical properties suitable forcontact lenses. Various cross-linkers are known in the art. Exemplarycross-linkers are triethylene glycol dimethacrylate (TEGDMA) andethylene glycol dimethacrylate (EGDMA).

Typically the polymerizable composition will additionally include acoloring agent such as a tint (e.g. Vat Blue 6) or a polymerizable dye(e.g. RB19-HEMA; see e.g. WO201302839). In specific examples, thepolymerizable composition consists of: (a) the HEMA-compatiblepolysiloxane, (b) the hydroxyalkyl methacrylate, (c) a monomer selectedfrom methacrylic acid, or acrylic acid, or glycerol methacrylate, or acombination thereof, and optionally (d) a cross-linker agent and/or apolymerizable dye, and no other polymerizable components.

There is no particular size constraint to the HEMA-compatiblepolysiloxanes described herein, but typically, they will have amolecular weight of at least 1K, 2K, or 3K, up to about 10K, 20K, or30K. In some examples, the silicone content of the HEMA-compatiblepolysiloxane is selected to provide the contact lens with an increase inoxygen permeability of at least 25%, 50%, 75%, or 100% compared to acomparable HEMA lens, where oxygen permeability (Dk) of the contact lensis measured in barrers using standard methods in the industry, such asby the method described by Chhabra et al. (2007), A single-lenspolarographic measurement of oxygen permeability (Dk) forhypertransmissible soft contact lenses. Biomaterials 28: 4331-4342. Forexample, if a contact lens made with a HEMA-compatible bifunctionalpolysiloxane, as described herein, has a Dk of 30 and a comparable HEMAcontact lens has a Dk of 15, the HEMA-compatible polysiloxane is saidprovide the contact lens with a 100% increase in oxygen permeability asdetermined by the equation: % increase=[(Dk_(H)−Dk_(C))/Dk_(C)]×100,where Dk_(H) and Dk_(C) are the Dk values of the HEMA-compatiblepolysiloxane-containing lens and the comparable HEMA contact lens,respectively. As used herein, a “comparable HEMA contact lens” is madefrom a polymerizable composition in which the HEMA-compatiblebifunctional polysiloxane is replaced by HEMA and optionally methacrylicacid, but is otherwise substantially identical. If needed, methacrylicacid is added to the comparative formulation in an amount to provide theresulting comparative lens with an equilibrium water content (EWC)similar to the HEMA-compatible polysiloxane-containing lens. To measureEWC, excess surface water is wiped off of the lens and the lens isweighed to obtain the hydrated weight. The lens is dried in an oven at80° C. under a vacuum, and weighed. The weight difference is determinedby subtracting the weight of the dry lens from the weight of thehydrated lens. The % EWC of the lens is =(weight difference/hydratedweight)×100. In various examples, the HEMA-compatible polysiloxane hasan average elemental silicon content of at least 8, 10, 12, 14, 16, 18,or 20 wt. % relative to the average molecular weight of theHEMA-compatible polysiloxane. In further examples, the HEMA-compatiblepolysiloxane-containing contact lens has an EWC of at least 30, 40 or 50wt. % and up to about 60 or 70 wt. %.

Exemplary HEMA-compatible bifunctional polysiloxanes, as noted above,comprise polyethylene oxide (PEO) groups, typically either as a sidechain to one or more of the siloxane groups (e.g. such as the p groupsin Formula 1), and/or as groupings adjacent the functional (i.e.polymerizable) ends of the polysiloxane (e.g. such as the k groups inFormula 1). Methods of making polysiloxanes comprising PEO groups aredescribed in U.S. Pat. No. 8,053,544, U.S. Pat. No. 8,129,442, and U.S.Pat. Publ. No. 2011/0140292. In a particular example, theHEMA-compatible polysiloxane has the structure of Formula 1, above,wherein k is an integer of 0 or 1, m is an integer of at least 6, n isan integer of at least 1, p is an integer of at least 1, and R₁ and R₂are independently selected from either hydrogen or a methyl group. Invarious such examples, m is an integer of at least 10, 15, 20, or 30 upto about 50, 60, 80, or 100; n is an integer of at least 1, 2, or 4 upto about 6, 8, 10, or 12. In another example, m is an integer within theaforementioned ranges, and n is an integer of at least 10, 15, or 30 upto about 40, 60, or 80. In various examples, k, m, and p are any of theaforementioned values, and R₁ is hydrogen. In such examples, thepolysiloxane may have a hydroxyl group content of at least 1 wt. %. Insome examples, the HEMA-compatible polysiloxane has an average hydroxylgroup content of from about 1, 2, or 3 wt. % up to about 5, 7, 10, or 15wt. %, wherein the wt. % of the —OH groups is based on the averagemolecular weight of the polysiloxane. We have found that polysiloxaneswith relatively high hydroxyl group content can be HEMA-compatibledespite having relatively low HLB values. Thus, in various examples, thepolysiloxane has an HLB value of 1, 2, 3 up to 5, 6, 7, or 8 and has ahydroxyl group content of from about 1, 2, or 3 wt. % up to about 5, 7,or 10 wt. %. In a specific example, the polysiloxane has an HLB value of3 to 5 and a hydroxyl group content of about 4 to 8 wt. %. As anexample, a polysiloxane of Formula 1, wherein k is 0, R₁ is hydrogen, R₂is a methyl group, m is 71, n is 50, and p is 1, has a hydroxyl groupcontent of about 6%, an HLB value of about 4, and is HEMA-compatible asdefined above without requiring water addition. In various otherexamples, the polysiloxane has the structure of Formula 1 wherein k is0, R₁ is hydrogen, R₂ is either hydrogen or a methyl group, m is aninteger of 6 to 100, n is an integer of 1 to 75, and p is an integer of1 to 40. In another example, the polysiloxane has the structure ofFormula 1 wherein k is 0, R₁ is hydrogen, R₂ is either hydrogen or amethyl group, m is an integer of 6 to 60, n is an integer of 1 to 10,and p is an integer of 10 to 30.

Methods for making the HEMA-compatible polysiloxanes and contact lensescomprising them are described in the Examples below. In a specificmethod, an intermediate polysiloxane of Formula 2:

wherein R₂ is either hydrogen or a methyl group, is prepared by reactingoctamethylcyclotetrasiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane and1,3-bis(3-methacryloxypropyl)-1,1,3,3-tetramethyldisiloxane andtrifluoromethanesulfonic acid, and neutralizing the reaction withmagnesium oxide. Next, a hydrosilyation reaction is used to attach aPEO-containing side chain to the intermediate polysiloxane of Formula 2to form a HEMA-compatible polysiloxane of Formula (3)

in which R₂ is hydrogen or a methyl group, and m, n, and p, have any ofthe values or combination of values indicated in the previousparagraphs. In a specific example, the HEMA-compatible polysiloxane hasa structure represented by Formula (3), wherein R₂ is a methyl group, mis an integer of 6 to 50, n is an integer of 1 to 6, and p is an integerof 8 to 20, and is miscible in HEMA to at least 30 wt. %. In a furtherexample, the polysiloxane has a structure represented by Formula (3)wherein R₂ is a methyl group, m is an integer of 6 to 25, n is aninteger of 1 to 4, and p is an integer of 12 to 18.

In various other examples, the HEMA-compatible bifunctional polysiloxanehas the structure of Formula 4:

wherein R₁ and R₂ are independently selected from either hydrogen or amethyl group, k is an integer of 0 or 1, m is an integer of 0 to 160, nis an integer of 1 to 75, p is an integer of 0 to 40, and q is aninteger of 0 to 20. In a specific example, m is an integer of 6 to 100,n is an integer of 1 to 75, p is an integer of 1 to 40, and q is 0. In afurther specific example, m is an integer of 6 to 60, n is an integer of1 to 10, p is an integer of 10 to 30, and q is 0.

In some examples, the HEMA-compatible bifunctional polysiloxane has thestructure of Formula 4, wherein m is 0, i.e. the polysiloxane does notcontain any polydimethylsiloxane (PDMS). In various such examples, thepolysiloxane has the structure of Formula 4 wherein m is 0, n is aninteger of 10 to 60, p is an integer of 0 to 6, q is 0, and R₁ ishydrogen. In a further example, the polysiloxane has the structure ofFormula 4 wherein m is 0, n is an integer of 20 to 40, and p is 0.Examples 8-10 below describe methods of synthesizing HEMA-compatiblebifunctional polysiloxanes having no PDMS.

In other examples, the HEMA-compatible bifunctional polysiloxanecomprises a side chain comprising units of ethylene oxide and propyleneoxide. In one such example, the HEMA-compatible bifunctionalpolysiloxane has the structure of Formula 4, wherein m is an integer of6 to 60, n is an integer of 1 to 10, p is an integer of 1 to 40, and qis an integer of 1 to 10. In a further example, the HEMA-compatiblebifunctional polysiloxane has the structure of Formula 4, wherein m isan integer of 6 to 50, n is an integer of 1 to 6, p is an integer of 8to 20, and q is an integer of 2 to 8. The synthesis of one suchexemplary polysiloxane is described in Example 7.

Provided herein are methods of purifying the HEMA-compatiblebifunctional polysiloxanes to remove unreacted PEG-containing reagents(e.g. OH-PEG allyl ether, PEG-polypropyleneglycol allyl ether, etc.). Inan exemplary method, the hydrosilyation reaction product (e.g. theHEMA-compatible polysiloxane, unreacted polyethylene glycol-containingreagent, and any other unreacted reagent) is combined with an organicsolvent and water, or with an organic solvent and an aqueous solution,to make a mixture. Suitable organic solvents include ethyl acetate,dichloromethane, and the like. Suitable aqueous solutions include salinesolution, sodium citrate, and the like. Agitation, such as vortexing orvigorous stirring, can be used to facilitate mixing the organic andaqueous phases. Next, the mixture is allowed to equilibrate into anorganic layer and an aqueous layer comprising unreacted PEG-containingreagents. Centrifigation can be used in the equilibrating step tofacilitate the phase separation. The aqueous layer is then discardedfrom the organic layer. The polysiloxane may be isolated from theorganic layer using standard techniques such as removing residualaqueous solution using dehydrating agents such as anhydrous sodiumsulfate, and removing organic solvent using air/gas flow, reducedpressure, increased temperature and/or a combination of these and othertechniques. Optionally, the organic layer may be recombined with wateror aqueous solution and the equilibrating and discarding steps repeatedone or more times until the desired degree of purity is reached. Invarious examples, the HEMA-compatible bifunctional polysiloxane ispurified to at least 85 wt. %, 90 wt. %, 95 wt. %, 98 wt. %, or 99 wt.%.

Optically clear contact lenses can be made from the HEMA-compatiblebifunctional polysiloxanes described herein using curing and otherprocessing methods known in the field. An exemplary method comprisespreparing a polymerizable composition comprising at least 25 wt. % of atleast one hydroxyalkyl methacrylate, at least 20 wt. % of aHEMA-compatible bifunctional polysiloxane, a polymerization initiator,and optionally 1 to 65 wt. % diluent. The polymerizable composition isfilled into a contact lens mold, which is typically made from athermoplastic polymer such as polypropylene. Typically, a first moldmember defining the front surface of the contact lens, referred to as a“female mold member”, is filled with an amount of the polymerizablecomposition sufficient to form a single polymeric lens body. A secondmold member defining the back (i.e. eye-contacting) surface of thecontact lens, referred to as the “male mold member”, is coupled to thefemale mold member to form a mold assembly having a lens-shaped cavitywith the amount of polymerizable composition therebetween. Thepolymerizable composition within the contact lens mold assembly is thenpolymerized using any suitable curing method. Typically, thepolymerizable composition is exposed to polymerizing amounts of heat orultraviolet light (UV). In the case of UV-curing, also referred to asphotopolymerization, the polymerizable composition typically comprises aphotoinitiator such as benzoin methyl ether, 1-hydroxycyclohexylphenylketone, Darocur or Irgacur (available from Ciba Specialty Chemicals).Photopolymerization methods for contact lenses are described in U.S.Pat. No. 5,760,100. In the case of heat-curing, also referred to asthermal curing, the polymerizable composition typically comprises athermal initiator. Exemplary thermal initiators include2,2′-azobis(2,4-dimethylpentanenitrile) (V-52),2,2′-Azobis(2-methylpropanenitrile) (V-64), and 1,1′-azobis(cyanocyclohexane) (V-88). In some examples, the polymerizablecomposition is thermally cured in a nitrogen oven. In a specificexample, the polymerizable composition comprises V-52 and is cured atabout 80° C. in air for about 1 hour.

At the completion of curing, the polymerized material between the moldmembers of the mold assembly has the shape of a contact lens, and isreferred to herein as a “polymeric lens body”. The male and female moldmembers are demolded, i.e. separated, and the polymeric lens body isremoved, i.e. delensed, from the mold member to which it is adhered.These processes are referred to as demolding and delensing,respectively, and a variety of such methods are known to those ofordinary skill in the field. In some methods, the demolding anddelensing processes can comprise a single process step, such as when themolds are separated using a liquid which also removes the polymeric lensbody from the mold. In other methods, such as when a dry-demoldingprocess is used, the polymeric lens body typically remains on one of themold members and is delensed in a subsequent process step. Delensing canalso be a wet or dry process. In one example, delensing is carried outby a “float off” method in which the mold member to which a polymericlens body is adhered is immersed in water. The water may optionally beheated (e.g. up to about 100° C.). Typically, the polymeric lens bodiesfloat off of the mold members in about ten minutes. In a specificexample, the polymeric lens body is dry-delensed from the mold prior tohydrating the polymeric lens body. Dry delensing can be carried outmanually, for example using tweezers to remove the polymeric lens bodiesfrom the mold member, or they can be removed using an automatedmechanical process, such as described in U.S. Pat. No. 7,811,483.Additional demolding and delensing methods for silicone hydrogel contactlenses are described in U.S. Pat. Publ. No. 2007/0035049.

After delensing, the polymeric lens body is washed to remove unreactedor partially reacted ingredients from the polymeric lens body and tohydrate the polymeric lens body. In a specific example, the polymericlens body is washed in a washing liquid free of volatile organicsolvents (e.g. methanol, ethanol, chloroform, etc.), and all liquidsused to wash the polymeric lens body are free of volatile organicsolvents. This type of washing may also be referred to herein as“organic solvent-free extraction” where “organic solvent” refers tovolatile organic solvents. For example, a washing step that uses aqueoussolutions of surfactants such as Tween 80, without any volatile organicsolvents, is considered to be a volatile organic solvent-freeextraction. In a further example, the polymeric lens body is notcontacted by any volatile organic solvents during the manufacturingprocess (i.e. from the time curing of the polymeric lens body iscomplete until the time it is sealed in its final packaging). While thepolymerizable compositions described herein can be used to makepolymeric lenses bodies that can be washed without the use of volatileorganic solvents, if desired, they can also be washed with organicsolvents. Thus, washing steps can include contacting the polymeric lensbody with a volatile organic solvent, such as a lower alcohol (e.g.methanol, ethanol, etc.), contacting the polymeric lens body withaqueous liquids that may or may not contain a volatile organic solvents,solutes, or combinations thereof. Exemplary washing methods aredescribed in U.S. Pat. Publ. No. 2007/0296914 and in Example 3 below.

After washing, and any optional surface modifications, the hydratedpolymeric lens body is typically placed into a blister package, glassvial, or other appropriate container, all referred to herein as“packages”, which contains a packaging solution, which is typically abuffered saline solution such as phosphate- or borate-buffered saline.The packaging solution may optionally contain additional ingredientssuch as a comfort agent, a hydrophilic polymer, a surfactant or otheradditive that prevents the lens from sticking to the container, etc. Thepackage is sealed, and the sealed polymeric lens body is sterilized bysterilizing amounts of radiation, including heat or steam, such as byautoclaving, gamma radiation, e-beam radiation, ultraviolet radiation,etc. The final product is a sterile, packaged optically clear siliconehydrogel contact lens.

The following Examples illustrate certain aspects and advantages of thepresent invention, which should be understood not to be limited thereby.

Example 1 Preparation of Polysiloxane Intermediate

202.20 g of octamethylcyclotetrasiloxane (LS8620, Shin-Etsu Chemical),21.87 g of 1,3,5,7-tetramethylcyclotetrasiloxane (LS8600, Shin-EtsuChemical) and 56.63 g of1,3-bis(3-methacryloxypropyl)-1,1,3,3-tetramethyldisiloxane (X-22-164,Shin-Etsu chemical) were added into 500 ml kjeldahl (eggplant-shaped)flask. To this solution 0.62 g of trifluoromethanesulfonic acid (WakoPure Chemical Industries) was added and stirred at 35° C. for 3 h. Afterthat 0.7025 g of magnesium oxide (light) (Wako Pure Chemical Industries)and 100 ml of hexane (anhydrous) were added and stirred for 1 h at roomtemperature. The reaction mixture was suction filtered through CeliteNo. 545 (Wako Pure Chemical Industries) and No. 5A KIRIYAMA filterpaper. The filtrate was evaporated and vacuum-dried at 35° C. Afterwardthe reaction mixture was gradually heated up to 165° C. at 1˜2 mmHg for30 min while stirring, and the low molecule impurity was stripped offfrom the organic phase under reduced pressure (ca. 1 mmHg) at 165° C.for 2 h. The reaction yielded 253.27 g of an intermediate siloxane ofFormula 2 (above).

Example 2 Preparation of HEMA-Compatible Polysiloxane Macromer

60.01 g of the intermediate siloxane of Formula 2, 83.43 g of hydroxylpolyethylene glycol allyl ether having an average molecular weight ofabout 750 (Uniox PKA5004, NOF Corporation), 120.00 g of 2-propanol(super dehydrated) (Wako Pure Chemical Industries), 0.60 g of 10%potassium acetate (Wako Pure Chemical Industries) in ethanol, 1.36 g of1% 2,6-di-t-butyl-4-methylphenol (Wako Pure Chemical Industries) in2-propanol and 0.69 g of 1% p-methoxyphenol (Wako Pure ChemicalIndustries) in 2-propanol were added into 500 ml eggplant-shaped flask.To this solution 1.20 g of 1% hydrogen hexachloroplatinate (IV)hexahydrate in 2-propanol (hereinafter 1% H2PtCl6/6H20/IPA) was addedand stirred at 50° C. for 2 h. After that the reaction mixture wasevaporated and vacuum-dried at 35° C. for 2 h. The reaction yielded146.05 g of which about 80% was a hydrophilic polysiloxane, designatedH10P16, having the structure of Formula 3 (above) wherein R₂ is a methylgroup, m is ˜20, n is ˜3, and p is ˜16. The polysiloxane had an HLBvalue of about 10 and a hydroxyl group content of about 1.2 wt. %. Theremaining components of the reaction product were about 16% allyl PEGand about 4% PEG.

Example 3 Preparation of contact lenses using HEMA-compatiblepolysiloxane, H10P16

The components listed in Table 1 when mixed together formed a clearcomposition. The component designated H10P16 was prepared using themethods described in Example 2 above.

TABLE 1 Unit Parts Component by weight H10P16 40 HEMA 60 MA 1.8 TEGDMA0.1 V52 0.5 Water 25

The mixture of Table 1 was filled into polypropylene contact lens moldsand air cured at 80° C. for 1 hour. The molds were opened and the moldhalf retaining the cured polymeric lens body was immersed into roomtemperature water for 20 minutes. During this time, the lenses hydratedand detached from the mold half. The lenses were then placed into freshwater for another 20 minutes at room temperature, then placed intocontact lens blisters containing 1.8 ml PBS, sealed and autoclaved. Theresulting lenses were optically clear, had an equilibrium water contentof about 55%, a Dk of about 38, and had acceptable physical propertiesand wettability.

Example 4 Preparation of contact lenses using HEMA-compatiblepolysiloxane, H8P16

The components listed in Table 2 when mixed together formed a clearcomposition. The component designated H8P 16 is a reaction productprepared using the methods described in Example 2 above, except that theratio of reactants was varied to provide a polysiloxane having astructure of Formula 3 wherein R₂ is a methyl group, m is ˜54, n is ˜7,and p is ˜17.

TABLE 2 Unit Parts Component by weight H8P16 40 HEMA 60 MA 1.8 TEGDMA0.5 V52 0.5 Water 25

The mixture of Table 2 was filled into contact lens molds, cured, andhydrated using the methods described in Example 3. The resulting lenseswere optically clear, had an equilibrium water content of about 56%, aDk of about 47, and had acceptable physical properties and wettability.

Example 5 Preparation of Dry-Delensable Contact Lenses UsingHEMA-Compatible Polysiloxane, H10P16

The components listed in Table 3 when mixed together formed a clearcomposition. The component designated H10P16 was prepared using themethods described in Example 2 above.

TABLE 3 Unit Parts Component by weight H10P16 30 HEMA 50 GMA 15 MA 2.5TEGDMA 0.5 V52 0.8 Water 20

The mixture of Table 3 was filled into polypropylene contact lens moldsand air cured at 80° C. for 1 hour. The molds were opened and the lenseswere mechanically removed from the mold half to which it was adhered(i.e. dry-delensed). The lenses were then placed into PBS for 20 minutesat room temperature, then placed into contact lens blisters containing1.2 ml PBS, sealed and autoclaved. The resulting lenses were opticallyclear, had an equilibrium water content of about 63%, a Dk of about 40,and had acceptable physical properties and wettability.

The same methods as described above for the formulation of Table 3 wereused to make optically clear, dry-delensable lenses of the formulationshown in Table 4 below.

TABLE 4 Unit Parts Component by weight H10P16 25 HEMA 70 GMA 0 MA 4TEGDMA 0.5 V52 0.8 Water 15

Example 6 Preparation and Purification of HEMA-Compatible Polysiloxane,H10P16

41.67 g of the intermediate siloxane of formula 2, 89.10 g of hydroxylpolyethylene glycol allyl ether having an average molecular weight ofabout 750 (Uniox PKA5004, NOF Corporation), 83.34 g of 2-propanol (superdehydrated) (Wako Pure Chemical Industries), 0.40 g of 10% potassiumacetate (Wako Pure Chemical Industries) in ethanol, 0.50 g of 1%butylated hydroxyl toluene in 2-propanol (hereinafter 1% BHT/IPA), and0.24 g of 1% 6-methoxyquinoline in 2-propanol (hereinafter 1% MQ/IPA)were added into a 300 ml eggplant-shaped flask. To this solution 0.80 gof 1% H2PtCl6/6H20/IPA was added and stirred at 50° C. for 2 h. Afterthat 0.8184 g of 1% NaHCO₃ aq. was added and stirred at room temperaturefor 1 hour. The reaction mixture was then evaporated and vacuum-dried at35° C.

The crude mixture was dissolved into 200 g of dichloromethane and 135 gof DI water was added. The solution was vigorously stirred and thencentrifuged at 1500 rpm, 5 min and 20° C. After that an upper layer wasremoved. This operation was repeated 4 times. To the organic layer 135 gof 1% NaCl aq. was added. The solution was vigorously stirred and thencentrifuged at 1500 rpm, 5 min and 20° C. Afterwards an upper layer wasremoved. This operation was repeated 13 times. The organic layer wasdried with Na₂SO₄ and filtrated. The filtrate was evaporated andvacuum-dried. To this solution 0.24 g of 1% BHT in IPA and 0.13 g of 1%MQ in IPA were added and then the solution was evaporated andvacuum-dried at 35° C.

The reaction yielded 73.83 g of a hydrophilic polysiloxane, designatedH10P16, having the structure of Formula 3 (above) wherein R₂ is a methylgroup, m is ˜20, n is ˜3, and p is ˜16.

Example 7 Preparation of HEMA-Compatible Polysiloxane, H15E75

202.20 g of octamethylcyclotetrasiloxane (LS8620, Shin-Etsu Chemical),32.78 of 1,3,5,7-tetramethylcyclotetrasiloxane (LS8600, Shin-EtsuChemical) and 58.61 g of1,3-bis(3-methacryloxypropyl)-1,1,3,3-tetramethyldisiloxane (X-22-164,Shin-Etsu chemical) were added into 500 ml kjeldahl (eggplant-shaped)flask. To this solution 0.62 g of trifluoromethanesulfonic acid (WakoPure Chemical Industries) was added and stirred at 35° C. for 5 h. Afterthat 0.7055 g of magnesium oxide (light) (Wako Pure Chemical Industries)and 100 ml of hexane (anhydrous) were added and stirred for 1 h at roomtemperature. The reaction mixture was suction filtered through CeliteNo. 545 (Wako Pure Chemical Industries) and No. 5A KIRIYAMA filterpaper. The filtrate was evaporated and vacuum-dried at 35° C. Afterwardthe reaction mixture was gradually heated up to 165° C. at 1 mmHg for 30min while stirring, and the low molecule impurity was stripped off fromthe organic phase under reduced pressure (1 mmHg) at 165° C. for 2 h.The reaction yielded 264.48 g of an intermediate siloxane of Formula 2.

The following were added into a 200 ml eggplant-shaped flask: 10.42 g ofthe intermediate siloxane of formula 2, 33.43 g ofpolyethyleneglycol-polypropylene-glycol allyl ether having an averagemolecular weight of about 750 and a random copolymer EO/PO molar ratioof about 75:20, respectively (Uniox PKA5004, NOF Corporation), 30.01 gof 2-propanol (super dehydrated) (Wako Pure Chemical Industries), 0.10 gof 10% potassium acetate (Wako Pure Chemical Industries) in ethanol,0.15 g of 1% butylated hydroxyl toluene in 2-propanol, and 0.08 g of 1%p-methoxyphenol (Wako Pure Chemical Industries) in 2-propanol. To thissolution 0.20 g of 11% H2PtCl6/6H20/IPA was added and stirred at 50° C.for 2 h; after 1 h of stirring, an additional 0.2 g of 1%H2PtCl6/6H20/IPA was added. Then the reaction mixture was evaporated andvacuum-dried. 0.07 g 1% BHT/IPA and 0.03 g 1% MQ/IPA were added to thedried reaction mixture and the solution was vacuum-dried again. Thereaction yielded 22.6069 g of a polysiloxane, designated H15E75-2k,having the structure of Formula 4 (above) wherein R₂ is a methyl group,k is 0, m is ˜15, n is ˜3, p is ˜12, q is ˜4, and R₁ is hydrogen. Thesiloxane had an HLB value of about 2.8 and a hydroxyl content of about1.2 wt. %.

Example 8 Preparation of Polysiloxane Intermediate

139.68 g of 1,3,5,7-tetramethylcyclotetrasiloxane (LS8600, Shin-EtsuChemical) and 30.00 g of1,3-bis(3-methacryloxypropyl)-1,1,3,3-tetramethyldisiloxane (X-22-164,Shin-Etsu chemical) were added into a 500 ml kjeldahl (eggplant-shaped)flask. To this solution 0.60 g of trifluoromethanesulfonic acid (WakoPure Chemical Industries) was added and stirred at 35° C. for 24 h.After that 0.70 g of magnesium oxide (light) (Wako Pure ChemicalIndustries) and 150 ml of hexane (anhydrous) were added and stirred for1 h at room temperature. The reaction mixture was suction filteredthrough Celite No. 545 (Wako Pure Chemical Industries) and No. 5AKIRIYAMA filter paper. The filtrate was evaporated and vacuum-dried at35° C. Afterward the reaction mixture was gradually heated up to 100° C.under reduced pressure (2˜3 mmHg) while stirring, and the low moleculeimpurity was stripped off from the organic phase at 100° C. for 2 h, andthen 120° C. for 1 h. The reaction yielded 157.86 g of an intermediatesiloxane of formula 5:

Example 9 Preparation of HEMA-Compatible Polysiloxane, H30P1-5K-NDM

15.00 g of the intermediate siloxane of formula 5, 32.75 g of2-(allyloxy)ethanol (Wako Pure Chemical Industries), 45.02 g of2-propanol (super dehydrated) (Wako Pure Chemical Industries), 0.30 g of10% potassium acetate in ethanol, 1.15 g of 1% BHT/IPA, and 0.08 g of 1%MQ/IPA were added into 300 ml eggplant-shaped flask. To this solution0.60 g of 1% H2PtCl6/6H20/IPA was added and stirred at 50° C. for 13.5h. After that the reaction mixture was evaporated and vacuum-dried at45° C. To this mixture 0.19 g of 1% BHT/IPA and 0.09 g of 1% MQ/IPA wereadded and then evaporated and vacuum-dried at 45° C. The reactionyielded 35.1547 g of a polysiloxane, designated H30P1-5K-NDM, having thestructure of Formula 3 (above) wherein R₂ is a methyl group, m is 0, nis ˜30, and p is 1. The siloxane had an HLB value of about 7 and ahydroxyl content of about 9.7 wt. %.

Example 10 Preparation of HEMA-Compatible Polysiloxane, H30AA-5K

10.02 g of the intermediate siloxane of formula 5, 15.52 g of allyalcohol (Wako Pure Chemical Industries), 25.04 g of 2-propanol (superdehydrated) (Wako Pure Chemical Industries), 0.20 g of 10% potassiumacetate in ethanol, 0.10 g of 1% BHT/IPA, and 0.05 g of 1% MQ/IPA wereadded into 300 ml eggplant-shaped flask. To this solution 0.40 g of 1%H2PtCl6/6H20/IPA was added and stirred at 50° C. for 13.5 h. After that0.4128 g of 1% NaHCO3 aq. was added and stirred for over 1 h at roomtemperature. Then the reaction mixture was evaporated and vacuum driedat 35° C. To this mixture about 5 g of acetone and 15 g of DI water wereadded with vigorous shaking. The mixture was then centrifuged (7000 rpm,5° C., 10 min). The upper (aqueous) layer was removed. This operationwas repeated three times in total. To this mixture 5 g IPA was added andthe reaction mixture was evaporated and vacuum-dried at 40° C. Then 0.06g of 1% BHT/IPA and 0.03 g of 1% MQ/IPA were added and then evaporatedand vacuum-dried at 45° C. The reaction yielded 16.6762 g of apolysiloxane, designated H30AA-5K, having the structure of Formula 3(above) wherein R₂ is a methyl group, m is 0, n is ˜30, and p is 0. Thesiloxane had an HLB value of about 3 and a hydroxyl content of about 13wt. %.

Although the disclosure herein refers to certain illustrated examples,it is to be understood that these examples are presented by way ofexample and not by way of limitation. The intent of the foregoingdetailed description, although discussing exemplary examples, is to beconstrued to cover all modifications, alternatives, and equivalents ofthe examples as may fall within the spirit and scope of the invention asdefined by the additional disclosure.

A number of publications and patents have been cited hereinabove. Eachof the cited publications and patents are hereby incorporated byreference in their entireties.

The invention further provides:

1. An optically clear silicone hydrogel contact lens comprising: apolymeric lens body that is the reaction product of a polymerizablecomposition comprising: a) at least 25 wt. % of at least onehydroxyalkyl methacrylate; and b) at least 20 wt. % of at least oneHEMA-compatible bifunctional polysiloxane comprising at least 6 siloxanegroups, wherein the HEMA-compatible bifunctional polysiloxane has an HLBvalue of at least 5, or has a hydroxyl group content of at least 1 wt.%, or has both an HLB value of at least 5 and has a hydroxyl groupcontent of at least 1 wt. %.

2. The contact lens of 1, wherein the HEMA-compatible bifunctionalpolysiloxane has a molecular weight of 1K to 20K.

3. The contact lens of 1 or 2, wherein the HEMA-compatible bifunctionalpolysiloxane has an elemental silicon content of at least 10 wt. %.

4. The contact lens of any one of 1-3, wherein the HEMA-compatiblebifunctional polysiloxane has the structure of Formula 4 (above) whereinR₁ and R₂ are independently selected from either hydrogen or a methylgroup, k is an integer of 0 or 1, m is 0 or an integer of at least 1, 6,10, 15, 20, or 30 up to about 50, 60, 80, 100, or 160, n is an integerof at least 1, 2, 4, 6, 8, 10, 12, 15, 20 or 30, up to about 6, 10, 20,30, 40, 60, 75, or 80, p is 0 or an integer of at least 1, 2, 4, 6, 8,10, 12 or 15, up to about 18, 20, 30, 40, or 60, and q is 0 or aninteger of at least 1, 2, 4, or 6 up to about 8, 10, 15 or 20.

5. The contact lens of any one of 1-4, wherein the HEMA-compatiblebifunctional polysiloxane has an HLB value of at least 7.

6. The contact lens of any one of 1-4, wherein the HEMA-compatiblebifunctional polysiloxane has an HLB value of less than 5 and a hydroxylgroup content of at least 1 wt. %.

7. The contact lens of any one of 1-4, wherein the HLB value is from 2to 4 and hydroxyl group content is from 4 to 8% wt. %.

8. The contact lens of any one of 1-7, wherein the polymerizablecomposition further comprises: c) 1 to 65 wt. % diluent, wherein the wt.% of the diluent is based on the total weight of the polymerizablecomposition, and wherein the diluent comprises water, a low molecularweight polyethylene glycol (PEG), or a combination thereof.

9. The contact lens of any one of 1-8, wherein the polymerizablecomposition further comprises at least 0.1% up to about 5% methacrylicacid or acrylic acid.

10. The contact lens of any one of 1-9, wherein the polymerizablecomposition comprises at least 35 wt. % of the hydroxyalkylmethacrylate.

11. The contact lens of any one of 1-9, wherein the hydroxyalkylmethacrylate is 2-hydroxyethyl methacrylate (HEMA).

12. The contact lens of any one of 1-11 having a Dk of at least 35.

13. The contact lens of any one of 1-11, wherein the polymerizablecomposition comprises a monomer selected from methacrylic acid, acrylicacid, glycerol methacrylate, and combinations thereof.

14. The contact lens of 13, wherein the polymerizable compositionoptionally comprises a crosslinking agent, a polymerizable dye, or botha crosslinking agent and a polymerizable dye, and no other polymerizablecomponents.

15. A method of manufacturing the optically clear contact lens of anyone of 1-14, comprising: a) polymerizing the polymerizable compositionto form the polymeric lens body; and b) hydrating the polymeric lensbody, wherein the polymerizable composition is either diluent-free orcomprises about 1 to 65 wt. % of a diluent consisting essentially ofwater or a low molecular weight PEG, or a combination thereof, whereinthe wt. % of the diluent is based on the total weight of thepolymerizable composition.

16. The method of 15, wherein the polymeric lens body does not come incontact with a volatile organic solvent during the hydrating step.

17. The method of 15 or 16, wherein the polymerizing step comprisesthermal curing in air.

18. The method of any one of 15-17, wherein the polymerizablecomposition is cured in a mold to form the polymeric lens body, andwherein the polymeric lens body is dry-delensed from the mold prior tohydrating the polymeric lens body.

19. A HEMA-compatible polysiloxane having the structure of Formula 4(above) wherein R₁ is hydrogen, R₂ is either hydrogen or a methyl group,k is an integer of 0 or 1, m is 0 or an integer of 1 or 6 up to 10, 30,50 or 60, n is an integer of at least 1, 2, 4, 6, 8, 10, 12, 15, 20 or30, up to about 6, 10, 20, 30, 40, 60, 75, or 80, p is 0 or an integerof at least 1, 2, 4, 6, 8, 10, 12 or 15, up to about 18, 20, 30, 40, or60, and q is 0 or an integer of at least 1, 2, 4, or 6 up to about 8,10, 15 or 20, wherein the HEMA-compatible bifunctional polysiloxane hasan HLB value of at least 5, or has a hydroxyl group content of at least1 wt. % based on the average molecular weight of the polysiloxane, orhas both an HLB value of at least 5 and has a hydroxyl group content ofat least 1 wt. %, and wherein the HEMA-compatible bifunctionalpolysiloxane has a purity of at least 75%.

20. The HEMA-compatible polysiloxane of 19 having a purity of at least90%.

21. The HEMA-compatible polysiloxane of 19 or 20, wherein theHEMA-compatible bifunctional polysiloxane has an HLB value of at least7.

22. The HEMA-compatible polysiloxane of 19 or 20, wherein theHEMA-compatible bifunctional polysiloxane has an HLB value of less than5 and a hydroxyl group content of at least 1 wt. %.

23. The HEMA-compatible polysiloxane of 19 or 20, wherein the HLB valueis from 2 to 4 and hydroxyl group content is from 4 to 8 wt. %.

24. The HEMA-compatible polysiloxane of 19 or 20, wherein k is 0.

25. A method of purifying a polysiloxane from a reaction productcomprising the polysiloxane and an unreacted polyethyleneglycol-containing reagent, said method comprising:

a) combining the reaction product with an organic solvent and water oran aqueous solution to make a mixture; b) equilibrating the mixture intoan organic layer and an aqueous layer; and c) discarding the aqueouslayer from the organic layer.

26. The method of 25, further comprising: d) combining the organic layerfrom step (c) with water or aqueous solution and repeating theequilibrating and discarding steps one or more times.

27. The method of 25 or 26, wherein the equilibrating step comprisescentrifuging the mixture.

28. The method of any one of 25 to 27 comprising separating thepolysiloxane from the organic layer.

We claim:
 1. An optically clear silicone hydrogel contact lenscomprising: a polymeric lens body that is the reaction product of apolymerizable composition comprising: a) at least 25 wt. % of at leastone hydroxyalkyl methacrylate; and b) at least 20 wt. % of at least oneHEMA-compatible bifunctional polysiloxane comprising at least 6 siloxanegroups, wherein the HEMA-compatible bifunctional polysiloxane has an HLBvalue of at least 5, or has a hydroxyl group content of at least 1 wt. %based on the average molecular weight of the polysiloxane, or has bothan HLB value of at least 5 and has a hydroxyl group content of at least1 wt. %, wherein the wt. % of the hydroxyalkyl methacrylate and theHEMA-compatible bifunctional polysiloxane is based on the total weightof polymerizable monomers in the composition.
 2. The contact lens ofclaim 1, wherein the HEMA-compatible bifunctional polysiloxane has thestructure of Formula 4:

wherein R₁ and R₂ are independently selected from either hydrogen or amethyl group, k is an integer of 0 or 1, m is an integer of 0 to 160, nis an integer of 1 to 75, p is an integer of 0 to 40, and q is aninteger of 0 to
 20. 3. The contact lens of claim 1, wherein theHEMA-compatible bifunctional polysiloxane has an HLB value of at least7.
 4. The contact lens of claim 1, wherein the HEMA-compatiblebifunctional polysiloxane has an HLB value of less than 5 and a hydroxylgroup content of at least 1 wt. %.
 5. The contact lens of claim 4,wherein the HLB value is from 2 to 4 and hydroxyl group content is from4 wt. % to 8 wt. %.
 6. The contact lens of claim 1, wherein thepolymerizable composition further comprises: c) 1 to 65 wt. % diluent,wherein the wt. % of the diluent is based on the total weight of thepolymerizable composition, and wherein the diluent comprises water, alow molecular weight polyethylene glycol (PEG), or a combinationthereof.
 7. The contact lens of claim 6, wherein the HEMA-compatiblebifunctional polysiloxane requires water addition for optical clarity.8. The contact lens of claim 1, wherein the polymerizable compositioncomprises from 0.1 wt. % up to about 5 wt. % methacrylic acid or acrylicacid.
 9. The contact lens of claim 1, wherein the polymerizablecomposition comprises at least 35 wt. % of the hydroxyalkylmethacrylate.
 10. The contact lens of claim 1, wherein the hydroxyalkylmethacrylate is 2-hydroxyethyl methacrylate (HEMA).
 11. The contact lensof claim 1, having a Dk of at least
 35. 12. The contact lens of claim 1,wherein the polymerizable composition comprises a monomer selected frommethacrylic acid, acrylic acid, glycerol methacrylate, and combinationsthereof.
 13. The contact lens of claim 12, wherein the polymerizablecomposition optionally comprises a crosslinking agent, a polymerizabledye, or both a crosslinking agent and a polymerizable dye, and no otherpolymerizable components.
 14. A method of manufacturing the opticallyclear contact lens of claim 1, comprising: a) polymerizing thepolymerizable composition to form the polymeric lens body; and b)hydrating the polymeric lens body, wherein the polymerizable compositionis either diluent-free or comprises about 1 to 65 wt. % of a diluentconsisting essentially of water or a low molecular weight PEG, or acombination thereof, wherein the wt. % of the diluent is based on thetotal weight of the polymerizable composition.
 15. The method of claim14, wherein the polymerizable composition is cured in a mold to form thepolymeric lens body, and wherein the polymeric lens body is dry-delensedfrom the mold prior to hydrating the polymeric lens body.
 16. AHEMA-compatible polysiloxane having the structure of Formula 4:

wherein R₁ is hydrogen, R₂ is either hydrogen or a methyl group, k is aninteger of 0 or l, m is an integer of 0 to 60, n is an integer of 1 to75, p is an integer of 0 to 40, and q is an integer of 0 to 20, whereinthe HEMA-compatible bifunctional polysiloxane has an HLB value of atleast 5, or has a hydroxyl group content of at least 1 wt. % based onthe average molecular weight of the polysiloxane, or has both an HLBvalue of at least 5 and has a hydroxyl group content of at least 1 wt.%, and wherein the HEMA-compatible bifunctional polysiloxane has apurity of at least 75%.
 17. The HEMA-compatible polysiloxane of claim16, wherein m is an integer of 6 to 60, n is an integer of 1 to 10, p isan integer of 10 to 30, and q is
 0. 18. The HEMA-compatible polysiloxaneof claim 16, wherein m is 0, n is an integer of 10 to 60, p is aninteger of 0 to 6, and q is
 0. 19. The HEMA-compatible polysiloxane ofclaim 18, wherein n is an integer of 20 to 40 and p is
 0. 20. TheHEMA-compatible polysiloxane of claim 16, wherein m is an integer of 6to 60, n is an integer of 1 to 10, p is an integer of 1 to 40, and q isan integer of 1 to
 10. 21. The HEMA-compatible polysiloxane of claim 16,wherein m is an integer of 6 to 50, n is an integer of 1 to 6, p is aninteger of 8 to 20, and q is an integer of 2 to
 8. 22. TheHEMA-compatible polysiloxane of claim 16, having a purity of at least90%.
 23. The HEMA-compatible polysiloxane of claim 16, wherein k is 0.24. A method of purifying a polysiloxane from a reaction productcomprising the polysiloxane and an unreacted polyethyleneglycol-containing reagent, said method comprising: a) combining thereaction product with an organic solvent and water or an aqueoussolution to make a mixture; b) equilibrating the mixture into an organiclayer and an aqueous layer; and c) discarding the aqueous layer from theorganic layer.
 25. The method of claim 24, further comprising: d)combining the organic layer from step (c) with water or aqueous solutionand repeating the equilibrating and discarding steps one or more times.26. The method of claim 24, wherein the equilibrating step comprisescentrifuging the mixture.